Bunuel wrote:
Of the test animals in a laboratory, 60% are brown rats and 40% are black rats. If the average brown rat weighs 9.2 ounces and the average black rat weighs 7.7 ounces, what is the average weight of a rat in the laboratory?
A. 7.7 ounces
B. 8.1 ounces
C. 8.45 ounces
D. 8.6 ounces
E. 9.2 ounces
We create the following equation for a weighted mean:
0.6(9.2) + 0.4(7.7) = 5.52 + 3.08 = 8.6
Do we have to write questions about test animals in laboratories? Isn’t there a better theme that we can
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